The market economy is the most successful mechanism for creating prosperity humanity knows. Allied to modern science, it has done more than transform the world economy; it has transformed the world. For the first time in history, the world’s principal states rely on the market economy to develop their economies. Almost as important, they rely on a global market economy. Contemporary states are destined to co-operate with one another if they are to prosper.Yet the market economy is not as unchangeable as the laws of the Medes and the Persians in the book of Daniel. It is successful not because it stays the same, but because it does not. The driving force is the desire of all human beings to work for the betterment of themselves and their families. The mechanism is the equally natural search for a better deal. But institutional settings and relationships with political institutions have always been open to change. This very adaptability has ensured the survival of market economies.

Two centuries ago there was no limited liability, no personal bankruptcy, little central banking, no environmental regulation and no unemployment insurance. All these changes occurred in response to economic or political pressures. All brought with them new solutions and new challenges. At a time of ongoing financial shocks, this need for adaptation has not ended. On the contrary, it is as important as ever.What, then, are the challenges that matter today? The libertarian movement in the US, whose standard-bearer is Ron Paul, is clear about the answer: abolish nearly all of these policy innovations and go back, as far as possible, to the capitalism of the late 19th century. Outside the US this current of opinion holds little sway. Even inside the US, it is merely a component of the Republican coalition. It is more than a mere curiosity – but it is not going to shape the future.More relevant is asking how far the resurgent capitalism that emerged in the 1980s, under the leadership of Ronald Reagan in the US and Margaret Thatcher in the UK, now needs to be reformed. The answer is that it must be, for it has proved not just unstable, but, in important respects, unjust. The result has not only been a devastating crisis, but also a sense that the achievement of extraordinary wealth may not reflect exceptional merit. In societies that rely on consent, this is politically corrosive.At the heart of the renewed debate are three issues: finance, corporate governance, and taxation. These are the questions raised by the “occupy” movements, which, for all their intellectual incoherence, have altered the terms of the political debate.The financial sector grew too big, partly because risks were misunderstood and partly because it was encouraged by policymakers to expand. It will need to be better constrained in future, partly by ensuring the risks it creates are internalised. Again, corporate management has too often rigged executive compensation in its own interests, rather than that of shareholders. Finally, a plethora of incentives have allowed many of the most successful people to escape taxation. In all these respects, the modern economy needs reform, to become both fairer and more efficient.Beyond such reforms, the debate over macroeconomic stabilisation that goes back to the 1930s has been renewed. In the years up to the crisis, the broad consensus was that a monetary policy targeted at inflation was enough. This view has been exploded. After the extended period of desperate improvisation now under way, a new synthesis will be required, one that takes proper account of asset prices, leverage and the role of central banks as lenders of last resort.Capitalism will endure, by changing. That is the lesson of the past. It is just as relevant today.